9. When did she start working here? ◊ How long has she been working here?

20. How long is it since you last sang this song? ◊ When did you last sing this song?

21. When did he last talk to you? ◊ How long has it been since he last talked to you?

III. Rewrite the following sentences

1. She has never read this book before. ◊ It is the first time she has read this book.

2. I haven't eaten this kind of food before. ◊ This is the first time I have eaten this kind of food.

3. I started work for the company a year ago. ◊ I've been working for the company for a year.

4. It started to snow at 5 o'clock. ◊ It has been snowing since 5 o'clock.

5. I last read a book on September 20th. ◊ The last time I read a book was on September 20th.